It is known that liquid dispensing pumps, when turned upside down or laid on a side during storage or shipping, have a tendency to leak out from the bottle. It is desired to have a dispensing pump that stops siphoning of liquid out from a container when the container is not in an upright position.
One such pump, a dispensing pump with positive shut off of a valve, such as a "duckbill" valve, is known. A duckbill valve is a hollow, elastomeric, one-way inlet valve with a ring-like base and inwardly tapering sidewalls terminating in a tip provided with a normally closed slit passage. The duckbill valve is used for controlling flow into and from a pump chamber because these valves operate reliably and are relatively inexpensive.
The disadvantage of such construction is that the user needs to depress a dispensing head of the pump and, while holding the dispensing head down, rotate the dispensing head with respect to an attached bottle to engage a threaded connection to close the duckbill valve. If the user desires to close the pump, but does not want nor need to discharge product therefrom, there is no method for doing so. In depressing the dispensing head, the product in the pump chamber of the pump bottle is discharged regardless. Accordingly, it is desired to have a dispensing pump where the duckbill valve may be shut-off without first dispensing the liquid from the bottle and without the need to depress and lock the head.
Another disadvantage is the cost of manufacturing this pump. Both an external and an internal thread formation is provided within the pump body to effect the twisting down of the cap and closing of the duckbill valve. These threaded formations are difficult to mold and increase the costs associated with the manufacturing of the pump dispenser. Further, there are critical tolerances in manufacturing pump sprays in order to have the parts work properly together. In this design, where there are a number of parts required, there is an increased cost for the parts and of manufacturing these parts with the required tolerances. As a result, the prior art pump is not economical to manufacture. An economically manufactured pump having less critical parts is therefore desired.